Rotor brake



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Pafenfed Apr.. 28,1942

OFFICE` ROTOR BRAKE Richard L. Smirl, Bellwood, Ill., assignor to Borg- Warner Corporation, Chicago, Ill., a corporation of Illinois Application November 22, 1940,1Serial No. 366,547

7 Claims.

devices are hydro-dynamic devices such as hydraulic torque converters and couplings.

against bell housing 24.

It has been proposedygto use hydraulic torque converters and couplings in automobile transmissions and particularly in combination with gearing to provide a transmission which may be substituted for the standard manually operated fric- Y a manner as to require the use of a jaw clutch,`

either to facilitate shifting or to provide a definite neutral position. Such a transmission, however, is not entirely satisfactory because the hydraulic torque converter at idling speeds of the engine transmits suiiicient torque to impose a load upon all the elements of the gearing and to cause the car to creep. With the elements of the gearing loaded, it is difficult, if not impossible,.to engage or disengage a positive clutch without the use of excessive and harmful force.

The object of this invention is to provide automatic means for preventing the transmission of torque from a hydraulic drive mechanism to gearing associated with the mechanism while the drive mechanism is rotating at low speeds corresponding to idling speeds of an automobile engine.

'Ihe preferred embodiment of the invention is shown in the accompanying drawing in which:

Fig. 1 isa side elevation, partly in section of a transmission embodying this invention; and

Fig. 2 is an elevation in section of the transmission taken along the line 2-22 of Fig. 1.

Referring now to the drawing for a detailed description of the invention, I is the drive shaft of an engine to which is bolted a iiywheel II. Said flywheel I I constitutes a portion of a torque converter I2 hailing a varied pump member I3, a vaned turbine or driven member It and an intermediate reaction member I which is varied to return the fluid from the turbine member I4 to the pump member I3. Turbine member I4 is splined, upon an intermediate shaft I5 which is connected by a jaw clutch I1 to a second shaft Il constituting the drive element of a change speed gear I9. Said change speed gear drives in turn a reversing mechanism 20, the details of which form no part of this invention and accordingly are omitted. The drive is then transmitted intermediate shaft I6.

from the reversing mechanism to driven shaft 2|.

Reaction member I5 is mounted upon a sleeve 22 `which may be held against rotation by a roller-and-cam type one-way brake 23 reacting The change speed gearing I9 comprises in the form illustrated, a sun gear 25, a ring gear 25, planet gears 2'I meshing with sun gear 25 and ring gear 26, and a carrier 28 for planet gears 2l, said carrier being mounted to rotate with shaft I8. A brake 29 is provided for sun gear 25 and a one-way clutch 30 prevents the sun gear from rotating faster than the carrier. Ring gear 26 constitutes the out-put member of the change speed gearing. When brake 29 is applied to sun gear 25, ring gear 2 6 is driven at an overspeed with respect to shaft I8, and when brake 29 is released, the reaction of the load on ring gear 26 will tend to cause sun gear 25 to rotate ahead of carrier 28 thereby causing one-way clutch 30 to come into play and lock the carrier to the sun gear. This latter condition results in a one-to-one, or direct, drive through the change speed gearing.

When it is desired to disconnect change speed gearing I9 completely from the engine, a jaw clutch Il', which is comprised of a slidable, internally toothed collar 3| cooperating with teeth 32 on the forward end of shaft I8, is operated (Fig. 1) to uncouple collar 3| from teeth 32 of shaft I8. To `reestablish the drive through the transmission, clutch I1 is-operated in a manner to couple teeth 32 with the teeth in 'collar 3l to lock shaft I8 to shaft I6.

It is a characteristic of hydraulic torque converters that at idling speeds of an engine associated therewith, a small. amount of torque, commonly referred to as drag torque, is still transmitted through the converter. When this drag torque is imposed upon `jaw clutch I'I a reestablishment of the drive through the clutch to the gearing becomes next toimpossible. To obviate this difficulty, an automatic brake 33 is provided for intermediate shaft I E which prevents the transmission of torque to the jaw clutch at idling speeds of the engine.

Referring now to Fig. 2, automatic brake 33 is comprised of a drum 34 which is rigid with bellhousng 24, and a plurality of brake shoes 35 which are mounted on a flange 36 secured to The mounting means for brake shoes 35 comprises leaf springs 31 which are so tensioned as to exert upon brake shoes 35 the amount of force necessary to stop the roment Il substantially above that normally imposed at idling speed, brake shoes 35 will be forciblyslid along the surface of drum 3l and rotated. When the speed of rotation of brake shoes 35 reaches a predetermined amount; the centrifugal force generated in these shoes by the rotation thereof will be sufficient to move them vradially oil` vbrake drum 34, thereby `removing completely all resistance to the rotation of turbine element I4.

Thus whenever the engine speed* is dropped down to idlingspeed, or whenever the engine is stopped completely, brake'\hoes 35 will engage brake drum 34 and arrest 'the rotation of in- 25 termediateshaft I6. Under such conditions jaw clutchv I1 may be operated to make or break the connection between the hydraulic torque converter and the speed change gearing I8. After the desired operation of jaw clutch II has been effected the engine may be speeded up and the increased torque resulting from such faster rotation of the engine will overcome the braking force of brake shoes 35 and will ultimately cause these brake shoes to rotate at such a speed as to lift them completely from drum 34.v

Although this invention has been described Awith reference to a hydraulic torque converter,"

it is understood that it is applicable to nontorque multiplying fluid couplings and in general to any devicev winch possesses the characteristics of transmitting torque as a function of the speed of the driving element thereof. It is understood also that other forms of change speedl gearing may be used and that the scope of the invention therefore is not to be limited to the form described above and illustrated in theY accompanying drawing but is to be determined by the appended claims.

I claim:

l. A hydro-dynamic torque-transmitting device comprising a driving element, a driven element hydraulically associated with the driving element, and a brake for the driven element, said brake being normally biased to engaged position to arrest the rotation of the driven element and arranged to allow rotation of the driven element above va predetermined torque on the driven element impressed thereon by the driving element through its hydraulic association therewith.

2. A hydro-dynamic torque-transmitting device comprising a driving element, a driven element hydraulically associated with the-driving element at all times, and a brake for the driven element, said brake being normally resiliently biased to engaged position to arrest the rotation of the driven element, and means operatively associated with the brake and `driven by said driven element and controlled by centrifugal force set up in said means for disengaging the brake above a predetermined speed of the driven element.

3. A4 hydro-dynamic torque-transmitting device comprising a pump element, means for driving the pump element at different speeds, including an idling speed, a rotor driven hydraulically from the pump element and adapted to transmit an appreciable amount of torque at idling speed, and brake means associated with the driven element and constantly biased to engaged position to arrest the rotation of the driven element, said bias being suflicient to overcome the torque on the rotor at idling speed of the pump element and allowing rotation of therotor at speeds of the pump element greater than idling speed, said brake means being arranged to disengage above a predetermined speed of the rotor.

4. A-hydrodynamic torque converter comprising a pump, a turbine and a stator, means for driving the pump at a plurality of speeds including an idling speed, a shaft connected to the turbine, a fixed frictional element, an element driven by the shaft, friction means adapt ed to cooperate withthe fixed element, and a leaf spring connecting the friction means with the driven element, said spring being initially flexed to cause the friction means to engage the friction element at idling speed of the-pump and arrest the rotation of the driven' element.

5. A hydro-dynamic torque converter comprising a pump, a turbine and a stator. means for driving the pump at a plurality of speeds in- .cluding an idling speed, a shaft connected to the turbine and driven thereby, a fixed drum, a flanged disc secured to the shaft, the flange of ysaid disc being radially spaced from the drum,

brake shoes intermediate the drum and ange and adapted to cooperate with the drum, and resilient means connecting the shoes for rotation with the flange, said means being initially compressed to bias the shoes to engaged position with a force which substantially equals the drag torque on theturbine when the pump is idling.

6. The combination described ,in claim 5, saidv 0 element, said bias being sufficient to overcome the torque at speeds no greater than vidling speed; said brake means comprising a fixed drum, radially operable brake shoes, and resilient means 'connecting the shoes to the rotor, said resilient means constantly biasingtthe shoes to engagement with the drum.

RICHARD L. vSMIRL. 

